Apparatus for grading fibers



Feb. 25, 1958 Amplifier s. w. BRIDGES ET Al.

APPARATUS FOR GRADING FIBERS Filed Aug. 25. 1954 Amplifier Device Device Couni'er Elec'i'ric Amplifier ATTORNEY a p- 21,824,488 ICCv patented `Feb. 25,: 1195s 1 l zgszmss- ArPARArUs ron GRADING FIERs;

.Southr Sudbury, lMass.,.assgnors to .National Research Corporation, Cambridge, Mass.,l a .corporation of Massachusetts` Application August 25,1954; Sel'al'No.v 452,016

3Claims. (Cl, SSL-14) arrangementof parts which are exemplified in the following detailed disclosure, and the .scope of the application of which will be; indicated in the claims.

rFor afullerlunderstanding ofv the nature. and'. objects of the invention, reference should be had to the following detailed description takenin connection with the accompanying drawing which'is a diagrammatic illustration of one .preferred embodiment of the. presentinvention.

. Throughout the various textile industries; stringent standards'have been established so` asl toresultinV auniform basis upon which fibers maybe graded or classified. Themeasurements ofthe average diameter and. diameter distribution of fibers are among the most important characteristics in determining the grade or fineness of fibers on which the ultimate price'and. end use of the fiberslargely depend. In the copending applications of Lawrence et al., SerialNo. 399,011, filed December 18, 1953, and Roehrig, Serial No. 452,015, filed on even date herewith, there are ldescribed several embodiments of apparatus which' has been' found successful in measuring the. average diameter and diameter distribution of fibers.

As .described in the aforementioned copending-applications,'. it has. been shown that the desired fiber measurements can be obtained by optically scanning groups of short sectioned fibers which have been aligned in` a-substantially parallel manner in the focal plane of a suitable optical scanningsystem. This' optical scanning system Apreferably comprises a source of light, a lens'system for forming a beam of light, a transparent support for holding the fibers to be scanned, and a photoelectric device responsive to changes in illumination. A group of fibers can be aligned by placing the fibers on a suitable grating and then picking these fibers from the grating by means of pressure-sensitive adhesive tape which will maintain the fiber alignment. The pressure-sensitive adhesive tape can then be secured to a microscope slide and passed through the optical system. The image of the fibers moving at a constant rate in a direction transverse of the fiber length is projected on the photoelectric device so as to produce electrical signals or pulses which bear a direct relationship to the diameter of the fibers scanned. These electrical signals containing width information are then fed to suitable counting circuits.

The present invention is directed to a modification of equipment of the above type which is specifically designed for determining relative percentages of different Samuel W. Bridges, Wellesley, and Jonathan R; Roehrig,

.to a-certain extent on the method ofmanufacture.

types vofrfibersin a-.givenfgroup' of=fibers.. .'Illezinvention is based on the'. discovery uthat many fibersexhibit significant optical anisotropy such that, for example, a plane polarizedlight, beam incident on theber in a direction other than parallel to the longitudinal .axis ofthefiber and having its plane of. polarizationy at an angle. other than 0 or 90 with respect to the-longitudinal axis of the fiberwi-ll beconverted' to ellipticallypolarized light by passing through thezfber. .The polarized. light passing throughy the fibers (aligned in a substantially parallel. relationship)l is .thus appreciably elliptically polarized by those fibers whichv are optically anisotropic... The degree of;anisotrop.y -of the .various fibers isl ai function ofv the type of fiber and' can, with certain artificial fibers', depend By utilizing suitable polarizers (supplemented in some cases by color filters) for examining the light beam. which is passedthroughnar'given fiber, its optical. anisotropycan be.readily'detected.A Whentheaopti'cal anisotropy of the fibergin a function yof wavelengthof the light, the color of the light beam which has passed through the fiber can `beernployeduto give a` further indication as to the type.r of. fiber under illumination.

The present invention will be particularly described in connection with. an apparatus rdesigned specifically for analyzingafigers to obtainV anzindication of the percentage of different types in a group; Thistype-distribution measurement canbein addition. to, .or in. lieu of,.`.a diameterdistribution measurement ofy the: type: described in. the aforementionedr applications of vLawrence et al. and Roehrig.4 Inxorderto distinguishbetween different types of fibers, the apparatus preferably comprises an optical vsystem.comprising alight sourceZ, a. polarizing filter 5,

acondensinglens 4, .a..transparent slide. 6 for carrying fibersinv substantially parallel alignment, means for movingsaid slide consisting; of atwheelor ygear 27 anda con- .stant speed motor 25,. and a projectionsystem 8 shown .photoelectric cell 12, an amplifier 14 and a counter 23.

This much of the-apparatus,` excluding the beam splitter 11, is made in: the manner. ,more fully describedfand claimed. in the abovementioned'application of Roehrig, filed on even datefherewith.. The. secondilight beam goes toa second electro-optical.y system*Y whichl comprises a polarizing filter 7a, a light filter 13, a` slit 9a `in a shield 10a, a photoelectriccell 12a, anamplifier 14a and a counter123a. The purpose of: the color f filter 13 is to differentiate betweenifiberswhose opticalvanisotropyis a function' of wave length.A For example, in. one embodiment Vof the invention,v the .filter 13 .iis minus-re'd-fsoy 'that it will block red light. Since nylon fibers appear red when placed between crossed polarizing filters, images of these bers will be blocked by filter 13 and the counter 23a will count only the white images corresponding to the wool fibers. Thus the counter 23 will count the total of nylon fibers and wool fibers while counter 23a will count only the wool fibers. The difference between these two counts will thus give the number of nylon fibers in the sample. The third electro-optical system preferably includes neither a polarizing filter nor a color filter but does have the corresponding slit 9b in the shield 10b, the photoelectric device 12b, the amplifier 14b and the counter 23b. Accordingly, it will count all fibers scanned by the optical system. Equally, although not indicated in the drawing, the third electro-optical system (9b, etc.) can include any suitable arrangement of one or more color filters to distinguish between various types of fibers. Thus, for example, when various fibers have different violet or infrared light, such differences in light transmission can be employed to distinguish between fibers having no optical anisotropy or having substantially constant optical anisotropy over the wave length range.

When employing the illustratedidevice, the sample to be analyzed is suitably prepared (as mentioned previously) and mounted on the transparent slide 6 `so as to be scanned by the optical system. .Theresultant image is then split by the beam splitter 11 and transmitted to the three or more electro-optical systems. .The first counter 23 will give a total count of all of those fibers which are sufficiently optically anisotropic to elliptically modify the plane of polarization enough so that the light passes through the polarizing filter 7. The ysecond counter 23a will count the same fibers as vthe` counter 23 minus those fibers whose optical properties are such that the resultant light approaching the electro-optical system is red in color. Thus, even though the light passes the polarizing filter 7a, it is still blocked by the minus-red filter 13.` Counter 23h will count all of the fibers. The various counters 23, 23a, 23b, etc., can be arranged to give (in addition to total count) a breakdown by size distribution, as described in complete detail in the above mentioned copending application of Lawrence et al. Equally, the counters can be interconnected so as to give a fiber count by optical characteristic. Thus, for example, the counter circuit can be arranged so that signals from counter 23a are automatically deducted from signals approaching counter 23 so that counter 23 will give only the wool count. Additionally, the signals from counters 23 and 23a can be deducted from the signals approaching counter 23b so that counter 23b gives only the total of optically isotropic fibers. As mentioned previously, the optically isotropic fibers can, if desired, be further analyzed by suitable color filters.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description, or shown in the accompanying drawing, shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. Apparatus for grading fibers as a function of their` optical properties, said apparatus comprising means for generating a beam of polarized light, means for holding a number of the fibers to be graded in substantially parallel relationship and in the focal plane of an optical system illuminated by said beam of polarized light, means for moving said holding means with respect to the polarized light beam so as to modify said polarized light beam by the optical property of each fiber in sequence, means for splitting the modified light beam into two light beams, the first of said beams being directed to a first electrooptical system and the second of said beams being directed to a second electro-optical system, a polarizing filter positioned adjacent the first electro-optical system for substantially preventing said first polarized beam from reaching said first electro-optical system unless said first polarized light beam has been modified by an optically anisotropic fiber, a color filter positioned adjacent the second electro-optical system for blocking light approaching said electro-optical system and having a predetermined color, and counting means controlled by said electro-optical systems for indicating the number of fibers detected by each of said two electro-optical systems.

2. Apparatus for grading fibers as a function of their optical properties, said apparatus comprising means for generating a beam of light, means for holding a number of fibers to be `graded in substantially parallel relationship and in the focal plane of an optical system illuminated by said beam of light, means for moving said holding means with respect to the light beam so as to modify said light beam by the opticalrproperty of each fiber in sequence, means for splitting the modified light beam into two light beams, the first of said beams being directed to a first electro-optical system and the second of said beams being directed to the second electro-opticalsystern, a filter positioned adjacent the first electro-optical system for substantially preventing said first beam from reaching said first electro-optical system when said first light beam has been modified by a fiber of a given color, a second color filter positioned adjacent the second electro-optical system for blocking light approaching said electro-optical system and having a second color, and counting means controlled by said electro-optical systems for indicating the number of fibers detected by each of said two electro-optical systems.

3. Apparatus for grading textile fibers comprising an optical system for projecting a beam of polarized light, means for holding a number of fibers in substantially parallel relationship in the beam of polarized light, means for creating relative motion transversely of the fiber length between the holding means and the light beam, a beam splitter for splitting said light beam into several portions, a plurality of electro-optical systems positioned to receive portions of the split beam, and counting means controlled by said electro-optical systems, two of said electro-optical systems including polarizing filters arranged to block portions of the polarized beam which have not passed through an anisotropic fiber, one of said two electro-optical systems additionally including a color filter forblocking light of a predetermined color, and a third electro-optical system arranged to detect optically isotropic as well as optically anisotropic fibers.

References Cited in the file of this patent UNITED STATES PATENTS 2,037,044 Reinartz et al. Apr. 14, 1936 2,299,983 Hertel Oct. 27, 1942 2,332,308 Dresser Oct. 19, 1943 2,413,486 Denyssen Dec. 3l, 1946 2,509,068 McMahon May 23, 195,0 FOREIGN PATENTS 731,095 Germany Feb. 1, 1943 

